THE BIRDS
SLENDER-BILLED NUTHATCH. Sitta carolinensis aculeata
Cassin
Field characters.Size
nearly that of Junco; tail about half length of body. Top of head and
back of neck black or slate-black; cheeks and under surface of body pure
white back slate gray. (See pl. 10e). Runs about readily on bark
of trees, moving in any direction. Voice: Song a series of double
notes all alike, cher-wer; call note a nasal
hank.
Occurrence.Resident in
Upper Sonoran Zone on west slope of Sierra Nevada where recorded from
near Lagrange and Merced Falls eastward to Smith Creek, east of
Coulterville; present in Transition and Canadian zones on west slope
except during midwinter; also found east of mountains (Mono Mills)
during summer season. Lives low on trunks and larger branches of both
coniferous and broad-leaved trees. Solitary.
The Slender-billed Nuthatch is the largest of the
three nuthatches found in the Yosemite region. Because it is fairly
common and does its foraging chiefly on the lower parts of the trees, it
is the species most likely to be seen.
The Slender-billed Nuthatch enjoys a wide
distribution in the Yosemite section. It is resident in the blue-oak
belt of the western foothills, and is found also, at least from spring
until early winter, in the Transition and Canadian zones. Its range on
the west slope extends from near Lagrange and Merced Falls eastward. The
easternmost summer record was made at Mono Meadow, a few miles south of
Glacier Point. In the early fall, as is shown by records from Ten Lakes,
McGee Lake trail, and the Clouds Rest trail near Little Yosemite Valley,
the birds invade the higher mountains. On the east slope of the
mountains Slender-billed Nuthatches were found at Mono Mills on June 7
and 10, 1916, and at Williams Butte, Walker Lake, and Warren Fork of
Leevining Creek, in the fall of 1915.
The three species of nuthatches of the Yosemite
section agree closely not only in general form of bill, wings, and tail,
but also in having bluish gray backs and in possessing white spots on
the outer tail feathers. (See pl. 10e, f, g). There are, however,
sharp differences between these birds, to be seen if looked for with
some little care. The Slender-billed is about twice the size of the
Red-breasted and Pigmy nuthatches and the entire side of its head or
'cheek' is white; the under surface of the body also is pure white. In
the other two birds the side of the head at least down to the eye is
dark, and the lower surface is not clear white. The adult male
Slender-billed has the top of the head silky black, whereas in females
this area is much duller. This difference in coloring affords a means
for distinguishing the sexes in the field.
The word nuthatch comes to us from the Old World
where it was first applied to a European relative of our birds which has
the habit of wedging nuts into crevices and then hacking them open. Our
nuthatches do considerable pounding with their bills both in digging
their nest holes and in breaking up food materials. Nuthatches,
creepers, and woodpeckers get most or all of their living on the trunks
and branches of trees, but the representatives of each of these groups
go after their food in different ways. The woodpeckers dig out grubs and
insects which burrow in or beneath the bark, while the other birds
mentioned get eggs, larvae, and adult insects which take shelter in the
furrows in the bark. Probably the smaller sized nuthatches and creepers
obtain, on the average, 'bugs' of smaller caliber than are sought out by
the woodpeckers. The bill of the creeper is a more delicate instrument
than that of the nuthatches. Its slender curved form makes possible to
the bird a farther reach, into the narrowest of crevices where small
insects lurk.
A creeper moves only upward on the trees, whereas the
nuthatches run about without reference to direction, and go up, down, or
crosswise seemingly with equal facility. The short tail of a nuthatch is
always carried in line with its back and gives the bird no support such
as the creeper obtains from its longer and stiff-pointed tail. The
nuthatches have long toes provided with stout, well-curved and
sharp-pointed claws, and these, catching in small irregularities in the
bark, enable the birds to cling readily, whatever their position with
reference to the pull of gravity. The bill is straight, rather strong,
and sharply pointed, and serves equally well in pulling insects out of
crevices, hacking open nuts or seeds, and in excavating or enlarging
nesting holes in rotten wood.
Nuthatches usually keep rather closely to their
distinctive mode of foraging; yet on one occasion, at Chinquapin, May
20, 1919, a Slender-billed Nuthatch was observed capturing flying
insects. The bird was clinging 25 feet above the ground on the trunk of
a tree, facing downward but with its head turned outward almost at right
angles with the trunk. Upon sighting a passing insect the nuthatch would
dart out, with undulating flight resembling that of a small woodpecker.
Its tail was spread so that the marginal white spots showed plainly.
With this short but broad 'rudder' the bird seemed to be able to change
direction easily while pursuing its winged prey. Upon making a capture
the nuthatch would alight upon some nearby tree, run along until an
appropriate place was found and then, turning head downward, would pound
the insect until it was in condition to swallow. Four or five perches
within a 50-foot radius were occupied thus during the few minutes that
this bird was under observation.
On the same date and at the same place another
Slender-billed Nuthatch was watched as it foraged about the bases of
the fir trees and on the ground. It seemed rather incongruous for this
bark searcher to descend and cross the needle strewn earth between
adjacent trees. The bird visited fifteen or so trees and fallen logs
during as many minutes but seemed to have no fixed forage beat as these
were not visited in any regular sequence. Rarely did the bird go far
above the ground; its highest excursion was not over 15 feet. On the
fallen logs it worked just as on standing trunks and if it disappeared
from sight its travels soon carried it back into view again.
The voices of the three species of nuthatches are
distinct. The call of the Slender-billed Nuthatch is a rather loud
hank or quank, repeated at varying intervals. This call
possesses somewhat of a nasal intonation but not so much of that quality
as there is in the call of the Red-breasted Nuthatch. The
Slender-billed never utters any high-pitched, clear, 'chattering' notes
such as are given by the Pigmy Nuthatch. In the spring the
Slender-billed Nuthatch gives a song which is a mere monotonous
repetition of a certain two-syllabled word: cher-wer, cher-wer,
cher-wer, etc.
The Slender-billed Nuthatch, at least in the Yosemite
section, ordinarily makes use of abandoned woodpecker holes for nesting
sites. In some other regions the birds are reported to dig out their own
nest holes, but here they seemingly find sufficient accommodation in the
numerous holes left by woodpeckers. Two instances of nesting were
recorded at Tamarack Flat on May 25, 1919, and a third near Pleasant
Valley on May 23, 1915. The first of the Tamarack Flat nests was 9 feet
above the ground in an old hole of the White-headed Woodpecker in a
broken off and barkless Jeffrey pine stump. The male bird was seen to
enter with a bill full of insects and there ensued at once from the
opening a series of low conversational notes. The contents of this nest
were not ascertained. The second nest, also in an abandoned White-head's
hole, was 7 feet (2130 millimeters) from the ground, measuring to the
top of the hole. The entrance was as made by the woodpeckers (1-3/4
inches or 43 millimeters in diameter), but the interior had evidently
been enlarged, by the nuthatches themselves, to a diameter of over 5
inches (130 mm.) and was filled to within 7-1/2 inches (190 mm.) of the
top, with deer and chipmunk hair and feathers from various birds. There
were seven slightly incubated eggs. The male kept uttering a special
alarm call, yek-yek-yek ek-ek-ek, and circulated about the
vicinity anxiously.
The female was on the nest and as she refused to
leave even during the hubbub incident to enlarging the entrance, the
observer had to lift her from the nest in order to examine the eggs. She
seemed to be in a sort of lethargy and did not struggle until actually
taken in hand. That the bird had not left the nest for some time was
evident from the quantity of excrement which was accumulated in the
cloaca. The condition of this female, the food supply which the male of
the first nest had been seen to take to his nest, and the further fact
that only males had been noted abroad for some days previously, led to
the belief that in this species the female alone carries on the duties
of incubation and that she remains upon the nest continuously for a
greater or less period of time, during which she is fed by the male. In
the case of the third nest, mentioned beyond as being seen in the
foothill country, and which contained young, both of the parent birds
were abroad, engaged in gathering food for the brood. These
observations, added to our knowledge of other species of birds, indicate
that only accurate observation of a species through the nesting season
will establish the exact relations existing in that species between the
sexes and between the adults and the young. It is unsafe to attempt to
predict the behavior of one species from consideration of the known
habits of other, even near-related, species.
Another nest of the Slender-billed Nuthatch was seen
on May 23, 1915, in a dead blue oak near Piney Creek not far from
Pleasant Valley. The two parent birds were busily engaged in capturing
and carrying insects to the young. The presence of a member of our party
6 feet below the nest caused obvious anxiety upon the part of the two
members of the pair who flew back and forth for twenty minutes before
one of them became courageous enough to enter and feed the brood. Soon
after the first had left, the other parent fed the young. Each again
filled its bill full of insects, but neither would venture into the nest
a second time; they flew back and forth uttering their curious little
notes, and in so doing did not seem to find it necessary to open the
bill at all.
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